GastrointestinalPrevalence and clinical relevance of Th17 cells in patients with gastric cancer

BackgroundTh17 cells have recently been identified as a distinct T helper (Th) lineage in a cancer animal model and in human cancers. Their specific role in tumor immunity is unclear. We, therefore, sought to evaluate the role of Th17 cells in gastric cancer.MethodsThe prevalence of Th1, Th2, Treg, and Th17 cells in both peripheral blood mononuclear cells (PBMC) and gastric tissue was evaluated by multicolor flow cytometry. The concentration of interleukin (IL)-17 in sera was quantitated by enzyme-linked immunosorbent assay.ResultsWe observed a clear difference in the prevalence of Th17 cells in PBMC (0.34 ± 0.24%) versus gastric cancer tissues (19.4 ± 12.1) (P = 0.0002). Subset-specific phenotypic analysis of CD4+ T cells in both PBMC and gastric cancer tissue showed that Th1 and Treg cells predominate in PBMC, whereas Th17 cells are the most abundant CD4+ T cell subset in cancerous tissue. The concentrations of IL-17, a hallmark of Th17, in gastric cancer patients and normal controls were 0.6 ± 0.67 and 0.16 ± 0.19 pg/mL (P = 0.0032). Five-year survival rates of patients with high IL-17 and low IL-17 concentration were 47.1% and 83.9% (P = 0.0075). Multivariate analysis indicated that IL-17 concentration was an independent prognostic indicator, as well as lymph node metastasis.ConclusionsThere was a significant skewing toward a Th17 phenotype in gastric cancer tissue. IL-17 seems to play an important role in the progression of gastric cancer.